Endurance exercise training initiated during senescence improved papillary muscle contractile function and ameliorated slower calcium transport of cardiac sarcoplasmic reticulum in old rats.
Does endurance exercise training improve cardiac sarcoplasmic reticulum calcium transport and contractile function in senescent rats?
Endurance exercise training initiated during senescence improves myocardial performance in rats, potentially by increasing calcium transport by the cardiac sarcoplasmic reticulum.
To determine whether endurance exercise training initiated during senescence improves the slower calcium transport of cardiac sarcoplasmic reticulum in senescent rats, three groups of male Fischer 344 rats were used: sedentary mature (SM), 11-12 mo of age; sedentary old (SO), 23-24 mo of age; and exercised old (EO), 23-24 mo of age. The EO rats ran on a motor-driven treadmill 5 days/wk for 8-10 wk while two other groups remained sedentary. The contraction duration of isometrically contracting papillary muscle was prolonged in the SO rats compared with the SM group, resulting from both a longer time-to-peak tension and a longer half-relaxation time. Chronic exercise improved the papillary muscle contractile function of the EO group to that observed in the younger SM rats. More importantly, the exercise regime ameliorated the slower oxalate-supported, ATP-dependent calcium transport observed in the SO group so that the EO and SM groups were the same. In contrast, the calcium-activated myosin adenosinetriphosphatase activity, which was slower in the SO group, was not altered after exercise training, so that both senescent groups were slower than the SM rats. Thus the increased calcium transport by the cardiac sarcoplasmic reticulum may be one of the potential mechanisms underlying the improvement of myocardial performance with chronic exercise initiated during senescence.
Tate et al. (1990) studied Senescence. Endurance exercise training vs. Sedentary was evaluated on Calcium transport of cardiac sarcoplasmic reticulum and papillary muscle contractile function. Endurance exercise training initiated during senescence improved papillary muscle contractile function and ameliorated slower calcium transport of cardiac sarcoplasmic reticulum in old rats.